Aims Atrial fibrillation (AF) ablation protocols using energy delivery with very high power and short duration (vHPSD) have been introduced to improve lesion formation. This study reports procedural data of vHPSD ablation in AF patients and analyses characteristics of ablation-induced left atrial (LA) scar formation from cardiac magnetic resonance imaging (MRI). Methods and results Sixty consecutive patients undergoing index pulmonary vein isolation following our institutional Q4U-AF workflow were prospectively enrolled. Ablation was conducted using a contact force sensing catheter allowing for vHPSD ablation using a temperature-controlled ablation mode. Thirty patients underwent cardiac late gadolinium enhancement MRI of the LA 3 months after ablation to assess LA scar.  Mean procedural duration was 66.5 ± 14.8 min. Mean ablation time was 4.7 ± 0.9 min with a mean number of 69.9 ± 14.2 applications. First-pass isolation was achieved in 51 patients (85%) for the right pulmonary veins (RPVs), in 37 patients (61.7%) for the left pulmonary veins (LPVs), and in 34 patients (56.7%) for both pulmonary veins (PVs). Magnetic resonance imaging at 3 months post-ablation demonstrated a mean scar width of 14.4 ± 2.6 mm around RPVs and 11.9 ± 1.9 mm at LPVs (P > 0.05). Complete PV encirclement was observed in 76.7% for RPVs, in 76.7% for LPVs, and in 66.7% for both PV pairs. During a mean follow-up of 4.7 ± 1.4 months, arrhythmia recurrence was observed in 3.3% of the patients. Conclusion Pulmonary vein isolation following a novel vHPSD workflow resulted in short procedure duration and high acute and mid-term efficacy. Magnetic resonance imaging demonstrated durable and transmural PV lesions with homogeneous and contiguous scar formation.

Aims: The present study aims to evaluate magnetic-resonance-imaging (MRI)-assessed left atrial strain (LAS) and left atrial strain rate (LASR) as potential parameters for the diagnosis of cardiac amyloidosis (CA), the distinction of clinical subtypes and differentiation from other cardiomyopathies. Methods and results: LAS and LASR were assessed by MRI feature tracking in patients with biopsy-proven CA. LAS and LASR of patients with CA were compared to healthy subjects and patients with hypertrophic cardiomyopathy. LAS and LASR were also analyzed concerning differences between patients with transthyretin (ATTR) and light chain amyloidosis (AL). A total of 44 patients with biopsy-proven CA, 19 patients with hypertrophic cardiomyopathy and 24 healthy subjects were included. In 22 CA patients (50%), histological examination identified ATTR as CA subtype and AL in the remaining patients. No significant difference was observed for reservoir, conduit or booster LAS in patients with AL or ATTR. Reservoir LAS, conduit LAS and booster LAS were significantly reduced in patients with CA and HCM as compared to healthy subjects (p < 0.001). Reservoir LAS and booster LAS were significantly reduced in CA as compared to HCM patients (p < 0.001). A linear correlation was observed between LA global reservoir strain and LA-EF (p < 0.001, r = 0.5), conduit strain and global longitudinal LV strain (p < 0.001, r = 0.5), global booster strain rate and LA-EF (p < 0.001, r = 0.6) and between global booster strain rate and LA area at LVED (p < 0.0001, 0.5). Conclusions: LAS and LASR are severely impaired in patients with CA. The MRI-based assessment of LAS and LASR might allow non-invasive diagnosis and categorization of CA and its distinct differentiation from other hypertrophic phenotypes.

Background: This study challenges state-of-the-art cardiac amyloidosis (CA) diagnostics by feeding multi-chamber strain and cardiac function into supervised machine (SVM) learning algorithms. Methods: Forty-three CA (32 males; 79 years (IQR 71; 85)), 20 patients with hypertrophic cardiomyopathy (HCM, 10 males; 63.9 years (±7.4)) and 44 healthy controls (CTRL, 23 males; 56.3 years (IQR 52.5; 62.9)) received cardiovascular magnetic resonance imaging. Left atrial, right atrial and right ventricular strain parameters and cardiac function generated a 41-feature matrix for decision tree (DT), k-nearest neighbor (KNN), SVM linear and SVM radial basis function (RBF) kernel algorithm processing. A 10-feature principal component analysis (PCA) was conducted using SVM linear and RBF. Results: Forty-one features resulted in diagnostic accuracies of 87.9% (AUC = 0.960) for SVM linear, 90.9% (0.996; Precision = 94%; Sensitivity = 100%; F1-Score = 97%) using RBF kernel, 84.9% (0.970) for KNN, and 78.8% (0.787) for DT. The 10-feature PCA achieved 78.9% (0.962) via linear SVM and 81.8% (0.996) via RBF SVM. Explained variance presented bi-atrial longitudinal strain and left and right atrial ejection fraction as valuable CA predictors. Conclusion: SVM RBF kernel achieved competitive diagnostic accuracies under supervised conditions. Machine learning of multi-chamber cardiac strain and function may offer novel perspectives for non-contrast clinical decision-support systems in CA diagnostics.

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Left-atrial (LA) strain is the result of complex hemodynamics, which may be better characterized using a multiparametric approach. Cardiovascular magnetic resonance (CMR) feature tracking was used to perform a comprehensive LA strain assessment of 183 enrolled healthy volunteers (11–70 years, 97 females, median 32.9 ± 28.3 years). Novel strain dependencies were assessed using multi-parametric regression (MPR) analyses. LA volumetric data, left ventricular strain, transmitral and pulmonary venous blood flow parameters were utilized to create clusters for MPR of all subjects and a heart rate controlled subgroup (pulse: 60–75/min, N = 106). The LA reservoir(r) and conduit(c) strains of the total cohort were significantly elevated (p ≤ 0.001) in women (r: 49.7 ± 12.9%, c: 32.0 ± 11.0%) compared to men (r: 42.9 ± 11.4%, c: 26.1 IQ 10.5%). In contrast, there were no gender-specific differences (p > 0.05) for subgroup LA reservoir, conduit and booster(b) strains (all, r: 47.3 ± 12.7%; c: 29.0 IQ 15.5%; b: 17.6 ± 5.4%) and strain rates (all, 2.1 IQ 1.0 s−1; − 2.9 IQ 1.5 s−1; − 2.3 IQ 1.0 s−1). MPR found large effect sizes (|R2|≥ 0.26) for correlations between strain and various cardiac functional parameters. Largest effect size was found for the association between LA conduit strain and LA indexed booster volume, LA total ejection fraction, left ventricular global radial strain and E-wave (|R2|= 0.437). In addition to providing normal values for sex-dependent LA strain and strain rate, no gender differences were found with modified heart rate. MPR analyses of LA strain/strain rate and various cardiac functional parameters revealed that heart rate control improved goodness-of-fit for the overall model.